Oscillating spreading arrangement for a combine harvester

ABSTRACT

Example embodiments relate to a combine harvester including a straw chopper having an inlet for unchopped straw, an outlet for chopped straw in an essentially horizontal direction, and a spreader fan, connected downstream of the outlet of the straw chopper and having an essentially horizontal plane of rotation, for spreading the chopped straw over a ground surface. The combine harvester further includes a guide member, which is arranged to deflect at least a part of the stream of chopped straw material to an axial intake of the spreader fan such that a part of chopped straw material meets the blades of the spreader fan in the direction of transport of the chopped straw material through the spreader fan at an acute angle (α) relative to the plane of rotation of the spreader fan.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.13/480,030 filed on May 24, 2012. Which is a Continuation of U.S.application Ser. No. 12/451,383 filed on Nov. 10, 2009, which is aNational Phase of PCT/SE2008/050725 filed on Jun. 17, 2008, which claimspriority from Swedish Application No. 0701510-0 filed on Jun. 20, 2007,the entire contents of each of which are herein incorporated byreference.

TECHNICAL FIELD

Example embodiments relate to a combine harvester including a strawchopper having an inlet for unchopped straw, an outlet for chopped strawin an essentially horizontal direction, and a spreader fan, connecteddownstream of the outlet of the straw chopper and having an essentiallyhorizontal plane of rotation, for spreading the chopped straw over aground surface.

BACKGROUND

Combine harvesters are becoming increasingly large and with ever widercutting tables to enable a field to be threshed in an effective manner.The cutting table is, in itself, essentially wider than the actualharvester. During threshing, crop residues, such as chaff and straw, aregenerated. Unless the straw is to be collected, it is usually choppedinto small pieces in a straw chopper, before it and the chaff aredistributed on the field to help provide nutrient for forthcoming crops.For a variety of reasons, it is desirable to spread the crop residuesbehind the combine harvester and to the sides, as evenly as possibleover a region essentially corresponding to the width of the cuttingtable. As the cutting tables become wider, it becomes increasinglydifficult to spread over the whole of the intended width. The strawchopper generates in the chopping kinetic energy, which is utilized tospread the residues over the field, and this energy is sufficient for awidth of about 8-9 m. When the cutting tables extend beyond 9 m, thiskinetic energy is no longer sufficient.

By arranging fans downstream of the straw chopper, it is possible tohandle and spread a larger quantity of crop residues and to do so overthe larger width. EP 1 031 273 shows a combine harvester of theabove-described type, which has fans for spreading the crop residues. Inthis solution, the outlet of the straw chopper is in the same plane asthe inlets of the fans so as not to lose kinetic energy from the strawchopper. One problem with this solution is that chopped straw can beforced back from the fans to the straw chopper and thus prevent choppedstraw from being blown out. In order to avoid this, large-diameter fanshave therefore been provided to prevent chopped straw from being blownback into the chopper. Only half the width of the fan can thus beutilized and, in principle, the fans therefore need to be twice as wide.With twice as wide fans, the equipment becomes not only more cumbersome,but also dearer and more complex.

The object of the invention is therefore to provide a straw chopperhaving a feed-out device to enable straw to be spread at least over awidth of about 9 m, but which, at least in part, is not afflicted by theabove-stated problems.

SUMMARY

Example embodiments of the present invention are achieved by a combineharvester which comprises a straw chopper having an inlet for unchoppedstraw, an outlet for chopped straw in an essentially horizontaldirection, and a spreader fan, connected downstream of the outlet of thestraw chopper and having an essentially horizontal plane of rotation,for spreading the chopped straw over a ground surface. The combineharvester has a guide member, which is arranged to deflect at least apart of the stream of chopped straw material to an axial intake of thespreader fan such that said part of chopped straw material meets theblades of the spreader fan in the direction of transport of the choppedstraw material through the spreader fan at an acute angle relative tothe plane of rotation of the spreader fan, whereby said part of thestream of chopped straw material contributes to the material movementthrough the spreader fan.

Such a spreader fan requires that a certain amount of energy is suppliedto enable the crop residues to be well spread over the harvested width.The guide member deflects the stream of chopped straw before it flowsinto the spreader fan in such a way that a certain part of the kineticenergy of the stream of chopped straw is utilized in the spreading ofcrop residues, for example chaff and chopped straw. An essentiallyhorizontal motional component of the stream of chopped straw is thusmaintained, which helps in the spreading of crop residues by virtue ofthe fact that the flow already has within it a certain movement from thestraw chopper in the rearward direction, calculated in relation to thedirection of travel of the combine harvester. In addition, this movementcan help to drive the spreader fan. This utilization of the movement ofthe straw from the straw chopper does not however mean that the spreaderfan is wholly dependent on an additional supply of energy from the strawchopper. Based on the requirements of the user in the individual case,there may be a need to drive the straw chopper and/or other materialtransport inside the combine harvester at different speed, therebyaffecting the movement of the chopped straw into, through and out of thespreader fan. The contribution which is nevertheless made by themovement is, however, always positive according to the presentinvention. Since a part of the kinetic energy of the chopped straw isutilized in the spreading, the necessary energy for driving of theoutlet fan can be reduced, i.e. a more compact fan motor with lowerpower can be used. Since the stream of chopped straw material is ledaxially into the spreader fan, the full width of the spreader fan can beutilized without chopped straw being returned to the straw chopper,which can result in a simple and compact construction of the spreaderfan. A straw chopper in combination with a spreader fan for spreadingcrop residues in a combine harvester can therefore be dimensioned in aresource-saving and compact and simple manner. The guide member ispreferably formed by a deflector plate, which is disposed, as seen inthe vertical direction, below or above the spreader fan.

Preferably, another part of the stream of chopped straw material isdeflected at a more obtuse angle relative to the plane of rotation ofthe fan than in the region in which the transport action of the fan isequidirectional with the incoming stream of chopped straw material. Itis therefore possible to brake the inflowing straw before it meets thefan blades in a region in which the straw would otherwise have brakedthem, i.e. in a region in which the transport action of the, fan isoppositely directed to the stream of chopped straw material from thestraw chopper. The straw therefore meets the fan blades without, inprinciple, any velocity, almost only vertically downwards towards theaxial intake of the spreader fan. The full width of the spreader fan canthus be utilized without unnecessary energy losses. A compact andlow-resource arrangement for spreading crop residues is thereforeprovided in a combine harvester. In this case, the guide member ispreferably configured as a deflector plate having a first portion fordeflecting a part of the stream of the chopped straw and a secondportion for deflecting another part of the strewn of the chopped straw.

The acute angle relative to the plane of rotation of the spreader fan ispreferably 10-40°, more preferably 20-30° and most preferably 23-28°,which, by thorough testing, has proved suitable for utilizing a part ofthe kinetic energy of the stream of chopped straw material.

The more obtuse angle relative to the plane of rotation of the spreaderfan is preferably 30-60°, more preferably 40-50° and most preferably43-48°, which, by thorough testing, has proved suitable for brakinganother part of the inflowing straw such that it does not inhibit theblades of the spreader fan in a region in which the transport action ofthe spreader fan is oppositely directed to the stream of chopped strawmaterial from the straw chopper. A part of the stream of chopped strawmaterial can thus be deflected such that it meets the fan bladeswithout, in principle, any velocity.

Preferably, the spreader fan has a front shield disposed along, a partof the periphery of the spreader fan, as seen in the circumferentialdirection. The shield helps the chopped straw to leave the spreader fanin the desired spreading direction and therefore prevents straw frombeing returned into the straw chopper and/or other parts of the combineharvester.

Preferably, the spreader fan has a front peripheral intake situated suchthat the transport action of the fan is equidirectional with thematerial flow feeding in through said peripheral intake. For example,the intake can be utilized to feed in chaff from a sieve unit in thespreader fan to enable it to be spread together with the chopped straw.It is thus possible to utilize the spreader fan also for even spreadingof, for example, chaff.

Preferably, the spreader fan has a collecting table fixedly attached tothe fan blades on their side facing away from the axial intake. Thecollecting table therefore forms a bottom of the spreader fan and canprevent crop residues from being axially conveyed out of the fan,regardless of the other spatial positioning of the spreader fan.

Preferably, the combine harvester additionally has a spreading member,which is pivotally disposed downstream of the spreader fan, saidspreading member being pivotable between a first and a second outerposition. In the first outer position, the stream of crop residues meetsthe spreading member at an angle which is greater than the angle atwhich the stream of crop residues meets the spreading member in thesecond outer position. When the spreading member is in the first outerposition, the stream of crop residues is deflected most in thecorresponding direction in relation to the combine harvester. When thespreading member is in the second outer position, the stream of cropresidues is deflected most in the corresponding other direction. In thisway, the spreading member, as it swings between its outer positions,helps the crop residues to be distributed in a manner determined by theuser of the combine harvester. The spreading member thus improves thespreading by the spreader fan, both in evenness and in width over thefield. As a result of its simple construction and hence low weight, thespreading member can swing faster than previously known variants, sothat the spreading of the straw can be almost continuous despite itsswinging motion. Furthermore, the swinging frequency can be adjusted sothat even spreading is obtained at different operating speeds of thecombine harvester and spreader fan respectively. In addition, thespreading member can be made to swing between other positions than saidouter positions to take account of, for example, wind conditions.

Preferably, the combine harvester comprises a second spreader fan, whichis disposed alongside and in the same plane as the first spreader fan.The second spreader fan preferably acts in the opposite motionaldirection relative to the first spreader fan. As a result of thissolution, a symmetrical appearance is obtained, which can beadvantageous by virtue of the fact that the respective spreader fan onlyserves the corresponding half of the combine harvester and that the twospreader fans can interact. The interaction between two symmetricallyplaced spreader fans can result in a simpler construction thereof. Inaddition, other parts than the spreader fans cart themselves beconstructed more simply. A further advantage is that each spreader fanis controlled individually, whereby wind conditions can be taken intoaccount.

Preferably, the spreading member is wedge-shaped and disposedessentially between two spreader fans, which allows the stream ofchopped straw material from two mutually adjacent spreader fans to beguided simultaneously. When the spreading member in this case is in oneouter position, the stream from one of the spreader fans is deflectedmost in this direction, whilst the stream from the other spreader fan isdeflected most in relation to “its” spreader fan. This latter means, byvirtue of the arrangement of two spreader fans, that the stream ofchopped straw material from this second spreader fan is deflecteddirectly rearwards about the center axis or line of symmetry of thecombine harvester. When the spreading member is instead in the otherouter position, the stream is deflected from the first spreader fandirectly rearwards about the center axis of the combine harvester,whilst the stream from the second spreader fan is deflected most. Bymaking the guide member swing between these two outer positions, evenspreading and full-width spreading of the chopped straw from twospreader fans is obtained.

The spreading member preferably has two essentially flat spreadingsurfaces, which are arranged to swing in tandem, each surface beingdisposed on the, in relation to the combine harvester, outer side of therespective spreader fan. It is therefore possible to control thespreading from the outlet of the respective spreader fan individually.

The spreading surfaces of the spreading member can be arranged to beindividually adjustable in relation to the respective spreader fan,which makes it possible to control the discharge of the respectivespreader fan in a variety of ways. The respective spreading surface canthus be given various outer positions in relation to its respectivespreader fan. This can be advantageous in the event of, for example,side wind.

Preferably, the rotation speed of the respective spreader fan isarranged to be controlled individually, which makes it possible, forexample, no adjust the spreading in dependence on wind conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in greater detail on the basis ofthe following drawings. The drawings should be regarded as purely forillustrative purposes and have no limiting effect. In the drawings,

FIG. 1 shows in side view a combine harvester having a straw chopperaccording to the present invention,

FIG. 2 shows in sectioned side view the rear part of the combineharvester in FIG. 1,

FIG. 3 shows a perspective view of selected parts of the combineharvester in FIG. 1,

FIG. 4 shows a perspective view of selected parts of the combineharvester in FIG. 1,

FIG. 5 shows in plan view the rear part of the combine harvester in FIG.1,

FIG. 6 shows schematically how crop residues are spread over a field,

FIG. 7 shows in plan view parts of the rear part of the combineharvester FIG. 1,

FIG. 8 shows a schematic side view of an alternative embodiment of thepresent invention,

FIG. 9 shows in plan view further alternative embodiment of the presentinvention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The combine harvester 1 shown in FIG. 1 is of otherwise conventionaltype, having a cutting table 4 with a pick-up drum 3 for gathering upstraw forage 5. The cutting table 4, together with the pick-up drum 3,is 9 m and above in width, which nowadays is becoming increasinglycommon so as to allow a field 9 to be harvested quickly and effectively.Within the combine harvester 1 there are then devices for separatinggrain from sterns (straw), chaff and other crop residues. These devicescomprise, for example, a sieve 6 (see FIG. 2) for sifting out chaff fromgrain, a straw shaker 7 (see FIG. 2) for guiding straw rearwards in thedirection of travel of the combine harvester 1, and a collecting bin(not shown) for the separated grain.

In this patent application, a reference to the directions “behind” and“in front of” relates to a position behind and in front, as seen in thenormal forward-directed direction of travel A of the combine harvester1.

In the rear part of the combine harvester 1 sits the straw chopper 2,arranged with two symmetrically placed spreader fans 8 according to thepresent invention. The straw chopper 2 is of conventional type and isarranged vertically below the rear end of the straw shaker 7. The strawchopper 2 has the task of chopping the straw if it is not to bewindrowed for subsequent collection, but is instead to be spread evenlyover the field 9. If the straw is chopped into smaller pieces, it ismore easily ploughed back into the ground and does not stick as easilyin a plough. Furthermore, it is more easily broken down and forms mulland contributes with nutrients to the next crop. It is thereforeimportant that the spreading of the straw is even over the field andover a width corresponding to the cut width represented by the cuttingtable 4.

The two spreader fans 8 have the task of spreading the straw in theabove-stated manner. Previous combine harvesters 1 of narrower widthhave not needed these, since the straw chopper 2, in the choppingoperation, has given the straw sufficient velocity, or kinetic energy,to be spread over the intended width. With the new wider combineharvesters 1, this kinetic energy is insufficient, but rather additionalvelocity is given to the straw in the spreader fans 8. In the preferredembodiment of the invention, the spreader fans 8 are arranged on onelevel vertically below and behind the straw chopper 2. The arrows 11represent the path of the chopped straw from the straw chopper 2 andinto the spreader fans 8, and out of the spreader fans 8.

Below the straw shaker 7, as seen in the vertical direction, is placedthe sieve 6. Not only may the straw need to be spread evenly over thefield 9, but also chaff needs to be distributed. Below the rear endportion of the sieve 6, as seen in the vertical direction, sit twosymmetrically placed chaff spreader fans 10. The arrows denoted by 12relate to the path of the chaff out of the chaff spreader fans 10 andout of the spreader fans 8, if the latter are also utilized for thespreading thereof. In an alternative but non-illustrated embodiment, thechaff spreader fans 10 can be pivoted about their axis and can insteadspread the chaff at a greater or lesser angle out from the sides of thecombine harvester 1. In this embodiment, the chaff does not thereforepass through the spreader fans 8.

FIG. 3 shows a perspective view of only parts of the spreader fans 8 inorder to illustrate their working. The spreader fans 8 sit side by sideand in the same plane. They each sit suspended about a respectiveessentially vertical shaft 17. The fans comprise fan blades 16, whichextend radially outwards from the shaft 17, and in their lower axialplane, as seen in the vertical direction, a disc 15 is disposed at therespective bottom edges of the fan blades 16. During use a cover isprovided, which is not shown in the figure. An opening 20 in this coveris present in the front edge of the cover and therefore the edge facingtowards the straw chopper 2. This opening 20 forms an inlet 20 forchopped straw. The opening 20 extends rearwards towards and ends closeto a guide plate 13 sitting transversely to the spreader fans 8. Whenthe guide plate 13 is connected to the opening 20, the cover's extensionis such that it covers the remaining parts of the spreader fans 8. Thisguide plate 13 extends continuously from a level above the opening 20downwards and rearwards towards the spreader fans 8. Its upper level, asseen in the vertical direction, is placed above the outlet opening 21 ofthe straw chopper 2, as seen in the vertical direction, as is shown inFIG. 2.

The guide plate 13 is divided into three portions 13 a, 13 b and 13 a. Afirst portion 13 a extends from one side of the combine harvester 1towards, but not right up to, the line of symmetry of the combineharvester 1. This first portion 13 a extends at least past the shaft 17of the spreader fan 8. The second portion 13 b begins where the firstportion 13 a ends and extends towards the other side of the combineharvester 1, but no further than up to the shaft 17 of the secondspreader fan 8 at the most. There the third portion 13 a then begins,which extends up to the other side of the combine harvester 1. In termsof shape and placement, the first and the third portion 13 a thereforemutually correspond. Together with the second portion 13 b, theytherefore form a guide plate 13 symmetrical about the line of symmetryof the combine harvester 1. The difference between the three portions 13a and 13 b is that they form different angles α, β to the spreader fans8. The first and the third portion 3 a thus form essentially the sameangle β to the spreader fans 8, whilst the second portion 13 b forms ashallower angle α than the first and third portion 13 a to the spreaderfans 8. In the transitions between the different portions 13 a and 13 bthere is a sealing plate 23, which is arranged to ensure that no choppedstraw from the straw chopper 2 is spread other than down into thespreader fans 8. The angle β in respect of the first and the thirdportion 13 a forms an angle of 40-50° to the plane of rotation of thespreader fans, whilst the second portion 13 b forms an angle α of 20-30to the plane of rotation of the spreader fans.

Along the periphery of the respective spreader fan 8 there is disposed abaffle plate 18. It extends from a level adjoining the discs 15, but isnot fixedly fitted to these, and vertically upwards to the leveladjoining the inlet openings 20. They thus shield the spreader fans 8 inthe radial direction. The baffle plates 18 run along the sides of thespreader fans 8 which face away from each other, i.e. on the outer sidesof the combine harvester 1, and along the sides facing in the directionof travel of the combine harvester, and follow essentially the roundedshape of the spreader fans 8. One end portion of the baffle plates 18 issituated in a position directly past the respective shaft 17 in thedirection of the second spreader fan 8 and viewed in the lateraldirection of the combine harvester 1. The baffle plates 18 extend alongthe periphery of the spreader fans 8 towards the respective other endportion thereof. This other end portion is situated directly past therespective shafts 17 of the spreader fans 8 viewed in the direction oftravel of the combine harvester 1, i.e. behind said shafts 17. This isbest illustrated in FIG. 5. In the preferred embodiment of theinvention, this position is occupied by the baffle plates 18 and relatesto a situation where the spreader fans rotate such that the straw isreleased from the fan blades 16 in the portion between the spreader fans8 and that they spread the straw rearwards.

In FIG. 3 there is also illustrated a spreading member 14, which isplaced between the spreader fans 8, essentially on the line of symmetrybetween them and directly behind the point where the spreader fans 8 areplaced closest together. The spreading member 14 is arranged as aV-shaped or wedge-shaped plate, with its apex placed forwards andpivotally suspended about a shaft 22. The angle of the plate is formedby the legs of the V and is fixed and adjusted to form the spreadingpattern, see FIG. 6 and as described in greater detail below. In thepreferred embodiment, the sides of the plate are flat in both thevertical direction and rearwards along its legs, but can conceivably beconcave in construction and at least partially follow the curvature ofthe periphery of the spreader fans 8. For stabilization of the spreadingmember 14, the two sides represented by the legs of the V are connectedto a further plate. In FIG. 5, the spreading member 14 is shown with asolid line in its one outer position and with a dashed line in its otherouter position, between which outer positions it is arranged to swing,as is illustrated with the arrow 19.

FIG. 4 shows in a perspective view somewhat different from FIG. 3 thespreader fans 8 and the guide plate 13. The figure illustrates theangles α, β between the different portions 13 a, 13 b of the guide plate13, in relation to the plane of rotation of the spreader fans 8. Theworking of the spreader fans 8 and the guide plate 13 will now bedescribed in greater detail. Unchopped straw is guided rearwards in thecombine harvester 1 with the aid of the straw shaker 7 and tumbles downinto the straw chopper 2. There it is cut by means of knives intosmaller pieces of chopped straw. The straw chopper 2 gives the choppedstraw a certain velocity rearwards in an essentially horizontaldirection, as is illustrated in FIG. 2 by the arrows 11. It meets inthis position the guide plate 13 and is deflected so as to be guideddownwards and rearwards into the spreader fans 8 through the inlet 20thereof. The spreader fans 8 give the chopped straw additional velocityin the rearward direction. The different portions 13 a and 13 b of theguide plate ensure that the chopped straw from the different transverseportions of the straw chopper 2 meet the fan blades 16 such that as muchvelocity as possible from the straw chopper 2 is preserved and utilizedto improve the spreading and reduce the energy required to drive thespreader fans 8. With the aid of the guide plate 13, the chopped strawis therefore given a, relatively speaking, acute angle α in relation tothe fan blades 16 in the portion 13 b in which the momentum of the strawis not to be halted, but rather the rotation R of the spreader fans 8shall interact with the velocity and direction of the straw, i.e.between the two shafts 17, for the spreading of the straw. In the twoportions 13 a in which the rotation R of the fan blades 16 would insteadbe impaired or inhibited by such an acute angle α, the angle is insteadsignificantly more obtuse β to allow the straw to meet the fan blades 16without, in principle, any velocity, almost only vertically downwardstowards the discs 15, so that the spreader fans 8 can execute thespreading in an optimal manner without unnecessary energy losses. Inthis way, the spreader fans 8 can be dimensioned and produced in aresource-saving mariner and their full width can be utilized, whichmakes them compact and not unnecessarily bulky.

In FIG. 5, the arrows 24 show the path of the chaff beneath the strawchopper 2 and through the spreader fans 8 if the chaff is to be mixedinto the straw. The baffle plate 18 also therefore ends in theabove-described position, so that a peripheral intake is formed toenable the chaff to be blown into the spreader fans 8 and guided furtherrearwards for additional spreading.

In order further to improve the spreading of the chopped straw over thefield 9, at least a part of the straw strikes the spreading member 14,which in normal operation is arranged to swing between its outerpositions at suitable frequency. The spreading member 14 can alsoconceivably swing more towards its one outer position, if the weatherconditions or other factors make this appropriate. In an extreme case,it can be set in a fixed position. FIG. 6 shows schematically how thechopped straw is spread over the field 9. The fact that the spreading ofthe straw is controlled by the spreading member 14 after the straw hasleft the spreader fans 8 in an oscillatory swinging motion over thefield 9, as is represented by the schematized windrows 25 a and 25 b,one windrow from each spreader fan 8, allows a very accurate control ofthe spreading of the straw. Previously known spreading members 14 can bebulky and hence sluggish and energy-intensive to run, with the resultthat they were also slow in their oscillation. With the spreading member14 according to the present invention, which is both simple andlightweight, the oscillation can be made faster and can hence spread thestraw better. A large number of oscillatory motions of the spreadingmember 14 means that two corresponding positions of the schematicwindrows 25 a, 25 b can come very close together.

FIG. 7 shows schematically how the spreading member 14 is arranged topivot about its shaft 22. A flywheel 27 is rotationally driven in aknown but non-illustrated manner, for example via a belt drive. A cardanshaft system 26 is eccentrically disposed on the flywheel 27 such that arotation of the flywheel 27 is converted by the cardan shaft system 26into a swinging motion of the shaft 22. The rotation of the flywheel 27can be adjusted such that the frequency is suitable for the intendeduse.

The spreading member 14 can be described as a device 14 for spreadingcrop residues over a field 9 and which, during use, is placed after astraw chopper 2 in a combine harvester 1, the device 14 having twovertical sides set at an angle to each other, which sides are pivotallydisposed about a vertical shaft 22. It should be pointed out that thespreading member 14 is not dependent on the spreader fans 8 for itsworking and construction, but can also work without spreader fans 8 asthese are described in the present invention. The same also applies tothe various embodiments of the spreading member 14 which are describedin the present application. However, there are additional advantages ifthese are provided together.

FIG. 8 shows a schematic view of an alternative embodiment of thepresent invention. In this, the spreader fans 8 are not placed,calculated vertically, below the outlet 21 of the straw chopper 2, butabove the same. The guide plate 13 is therefore instead placed below theoutlet 21 and the stream of chopped straw is led at corresponding anglesα and β into the spreader fans 8, the inlet openings 20 of which, inthis embodiment, are therefore placed on the bottom side, whilst thediscs 1 are placed on the top side.

FIG. 9 shows a further alternative embodiment. In this embodiment, thetwo spreader fans 8 rotate in the opposite direction R to that shown inprevious figures. Instead of a wedge-shaped spreading member 14symmetrically between the two spreader fans 8, two essentially straightvertical plates 14 are thus disposed in corresponding placement in thedirection of travel A of the combine harvester 1, but one on each outerside of the spreader fans 8. In this embodiment, chaff is admitted oneach outer side of the spreader fans 8. Thus, the baffle plate 18 andits connection along the periphery of the spreader fans 8 is insteadsuch that it fully closes off the spreader fans 8 in the radialdirection on their mutually facing sides. On the other hand, it allowschaff to be admitted in the radial direction into the spreader fans 8 ontheir sides facing away from each other, i.e. on the outer sides of thecombine harvester.

The above-described embodiments are not limited to the concept of theinvention, but describe only the currently preferred embodiments. Withinthe scope of the invention, many other variants can be envisaged and,for example, the angles of the guide plate 13 are not limited to thosespecified above, as long as the principle of its contribution tomaintaining the velocity of the straw between the shafts 17 ismaintained. Other differences are the type of combine harvester 1 andstraw chopper 2, which, in itself, does not have any major bearing uponthe present invention. For example, instead of a straw shaker 7 therecan be rotors. Furthermore, the full width of the whole of the spreaderfans 8 does not necessarily need to be utilized, but rather a greaterpart of the chopped straw can be fed into them towards the line ofsymmetry should this be deemed advantageous. The use of just onespreader fan 8 may also be envisaged. In addition, it is possible tocontrol the spreader fans 8 and the spreading member 14 individually.

1. A spreading arrangement adapted to be arranged after a straw chopperof a combine harvester, said spreading arrangement comprising: twospreader fans; and a spreading assembly, including two spreadingsurfaces and two shafts, wherein the two spreading surfaces are arrangedto swing in tandem, wherein one of the two spreading surfaces ispivotally suspended about one of the two shafts, and wherein the otherspreading surface is pivotally suspended about the other of the twoshafts, said spreading assembly disposed downstream of said two spreaderfans such that the spreading assembly controls the spreading of strawsafter the straws have left the two spreader fans, and said spreadingassembly operable to move in an oscillating frequency so as to spread atleast a part of chopped straws at the oscillating frequency, wherein thespreading assembly is configured to oscillate along a plane that isparallel to a plane of rotation of the two spreading fans, and whereinthe two shafts do not coincide with the spreader fans' rotation axes. 2.The spreading arrangement of claim 1, wherein said spreading surfacesare flat.
 3. The spreading arrangement of claim 1, further including aflywheel coupled to said spreading assembly to convert rotationalmovement of said flywheel into a swinging motion of said shafts.
 4. Thespreading arrangement of claim 3, wherein said oscillating frequency ofsaid spreading assembly is adjustable based at least in-part on rotationof said flywheel.
 5. The spreading arrangement of claim 1, wherein saidtwo spreader fans are configured to rotate in opposite rotationaldirections to guide the chopped straw towards a back end of said combineharvester.
 6. The spreading arrangement of claim 1, wherein said twospreader fans are positioned at a level vertically above and downstreamfrom an outlet of said straw chopper to allow the chopped straw to bereceived by said two spreader fans from a bottom side thereof.
 7. Thespreading arrangement of claim 1, further including a baffle plate alonga portion of a periphery of said spreader fans to form a structure thatcloses off access to said spreader fans on mutually facing sides of saidspreader fans, wherein another portion of the periphery of said spreaderfans that is not covered by said baffle plate allows chaff to beadmitted into said spreader fans on sides facing away from each other.8. The spreading arrangement of claim 1, further including a guide platefor guiding at least part of said chopped straw into said spreader fans.9. The spreading arrangement of claim 8, wherein said guide plateincludes multiple sections that together form said guide platesymmetrical about a line of symmetry of said combine harvester.
 10. Thespreading arrangement of claim 1, wherein each spreading surface extendsfrom a corresponding shaft.
 11. A spreading arrangement adapted to bearranged after a straw chopper of a combine harvester, said spreadingarrangement comprising: two spreader fans; a spreading assembly,including two spreading surfaces and two shafts, wherein the twospreading surfaces are arranged to swing in tandem, wherein one of thetwo spreading surfaces is pivotally suspended about one of the twoshafts, and wherein the other spreading surface is pivotally suspendedabout the other of the two shafts, said spreading assembly disposeddownstream of said two spreader fans such that the spreading assemblycontrols the spreading of straws after the straws have left the twospreader fans, and said spreading assembly operable to move in anoscillating frequency so as to spread at least a part of chopped strawsat suitable frequency; and a guide plate for guiding at least part ofsaid chopped straws into said spreader fans, wherein said guide plate ispositioned below said straw chopper, and wherein the two shafts do notcoincide with the spreader fans' rotation axes.
 12. The spreadingarrangement of claim 11, wherein said guide plate includes multiplesections that together form said guide plate symmetrical about a line ofsymmetry of said combine harvester.
 13. The spreading arrangement ofclaim 11, wherein said spreading surfaces are flat.
 14. The spreadingarrangement of claim 11, further including a flywheel coupled to saidspreading assembly to convert rotational movement of said flywheel intoa swinging motion of said shafts.
 15. The spreading arrangement of claim11, wherein said oscillating frequency of said spreading assembly isadjustable based at least in-part on rotation of said flywheel.
 16. Thespreading arrangement of claim 11, wherein said two spreader fans areconfigured to rotate in opposite rotational directions to guide choppedstraw towards a back end of said combine harvester.
 17. The spreadingarrangement of claim 11, wherein the spreading assembly is configured tooscillate along a plane that is parallel to a plane of rotation of thetwo spreading fans.
 18. The spreading arrangement of claim 11, whereinsaid two spreader fans are positioned at a level vertically above anddownstream from an outlet of said straw chopper to allow the choppedstraw to be received by said two spreader fans from a bottom sidethereof.
 19. The spreading arrangement of claim 11, further including abaffle plate along a portion of a periphery of said spreader fans toform a structure that closes off access to said spreader fans onmutually facing sides of said spreader fans, wherein another portion ofthe periphery of said spreader fans that is not covered by said baffleplate allows chaff to be admitted into said spreader fans on sidesfacing away from each other.
 20. The spreading arrangement of claim 11,wherein each spreading surface extends from a corresponding shaft.